| 1973. | Cymatium (Monoplex) echo Kuroda & Habe Oyama, K. 1973 p. 78, pl. 9, fig. 3 |
| 1954. | Cymatium (Monoplex) echo Kuroda & Habe Taki, I. & Oyama, K. 1954 pl. 1, fig. 9 PreviousNo: 21823 |
| 1911. | Triton costatus Born Yokoyama, M. 1911c p. 8, pl. 1, fig. 9 PreviousNo: 21823 |
| Condition: | Present |
| Taxonomy: | Mollusca: Gastropoda: Ranellidae: |
| Geologic Time: | Cenozoic: |
| Oyama, K., 1973: Revision of Matajiro Yokoyama's type Mollusca from the Tertiary and Quaternary of the Kanto area. Palaeontological Society of Japan, Special Papers, no. 17, pp. 1–148, pls. 1–57. (Reference No. 0411) |
| Taki, I. and Oyama, K., 1954: Matajiro Yokoyama's the Pliocene and later faunas from the Kwanto region in Japan. Palaeontological Society of Japan, Special Papers, no. 2, pp. 1–68, pls. 1–49. (Reference No. 0441) |
| Yokoyama, M., 1911c: Climatic changes in Japan since the Pliocene epoch. Journal of the College of Science, Imperial University of Tokyo, vol. 32, art. 5, pp. 1–16, pl. 1. (Reference No. 0462) |
 |
| Ichikawa, T., 1983, no. 9, p. 148. |
| Ichikawa, T., 1983, no. 9, p. 215. |
| Ichikawa, T., 1983, no. 9, p. 251. |
